A Kazakh-born Republican candidate for City Council, Oleg Gutnik, has charged that the incumbent Democrat, Michael Nelson, is guilty of “pure discrimination” against immigrants because of Mr. Nelson’s challenges to the signatures of Russian-speaking voters on Dr. Gutnik’s ballot-access petition.

An election attorney in Sheepshead Bay, Brooklyn, Theodore Alatsas, who represented Dr. Gutnik — the candidate is an obstetrician-gynecologist — in the petition fight, said that at the end of Board of Elections hearings yesterday, the Republican had survived Mr. Nelson’s challenges, with the board recognizing about 850 of Dr. Gutnik’s signatures as valid. The candidate had filed about 1,250 signatures last month, more than double the 540 signatures he needed to win a spot on the ballot.

Mr. Alatsas said he received a phone call yesterday afternoon from Mr. Nelson’s attorney in the petition dispute, state Senator Martin Connor, Democrat of Brooklyn Heights, who told him the Nelson campaign will ask a state Supreme Court judge in Brooklyn, Joseph Levine, to knock Dr. Gutnik off the ballot. Justice Levine is scheduled to hear Mr. Connor’s motion this morning.

Mr. Connor did not return telephone calls requesting comment.

Mr. Alatsas said signatures from immigrants who lived in the former Soviet Union are more vulnerable to challenges because those voters, in keeping with Russian-language norms, often write only their first initial, rather than their full given name, on ballot-access petitions. Moreover, Mr. Alatsas said, “Their penmanship tends to be similar, and is generally characterized by a slight slant to the right.” According to Mr. Alatsas, immigrants who learned the Cyrillic alphabet as children often eschew the “whooping swirls” typical of cursive script. Instead, they print block letters and then connect the individual characters. As a result, Mr. Alatsas said, entire pages of signatures sometimes appear as if they were written by the same hand.

Mr. Alatsas said the Nelson camp did not challenge signatures from American-born residents of the district, which includes Sheepshead Bay, Brighton Beach, Manhattan Beach, and Midwood.

Mr. Nelson, a third-term incumbent from Sheepshead Bay, responded to the Gutnik camp’s allegations by saying, “You have to ensure that people are living up to the law in order to preserve the integrity of the electoral process. Everyone has to play by the same rules.”

Both Dr. Gutnik and Mr. Nelson mounted challenges to the Republican ballot-access petition filed by a third candidate, Michael Roth. Mr. Alatsas defended his client’s successful bid to kick his potential primary opponent off the ballot. “Mr. Roth’s petitions were thrown out because he had a Democrat going around collecting signatures, and that is a violation of state law,” Mr. Alatsas said. Although Mr. Roth has been disqualified as a Republican candidate, he is still running on the Independence line.